Art or process of liquefying air and separating it into oxygen and nitrogen.



J. F. PLACE.

ART 0R PROCESS OF LIQUEFYING AIR AND SEPARATING IT INTO OXYGEN AND NITROGEH.

APPLICATION FILED NOV. 9. I911- Patented Aug. 31,1915.

I or Process-of Liquefying Air and Separating It Into Oxygen-and Nitrogen, of which OFFICE? JAMES F. PLACE, OF GLEN amen; new annsnmnssxenon. To .enunmcau AIR.-

LIQUEFYING COMPANY, on NEW YORK, n. Y., A CORPORATION or NEW YORK.

ART R PROCESS OF LIQUEFYING- AIR AND SEPARATING IT INTO OXYGEN AND NITROGEN. i l

To all whomit may concern:

Be it known that I, JAMEs F. PLACE, a citizen ofthe United States, and resident of Glen Ridge, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in the Art the following is a specification.

My invention relates to an improved art or process of liquefying atmospheric air,

and separating the same into its constituents oxygen and nitrogen. It is also equally adapted to liquefying and separating other gaseous mixtures, especially when composed like air of gaseshaving different tempera tures of liquefaction.

The object is to simplify the process, and

more thoroughly separate the constitutents of air, oxygen and nitrogen, or of other gaseous mixtures. J v

A special feature of this invention is the advantageof using only one compressor; for

' by this process the air compressor which supplies air to the liquefier, supplies the air or other gas required by an expansion en-' gine which is employed for producing low temperatures by converting heatinto recoverable-external work, and also the air needed for rectification by fractional distillation of the liquefied gases with recovery of new liquid thereby, in the liquefying coils and rectifying column'so that practically only one pressure of air or of its constituent gases is used. i

In carrying out my process I employ the unliquefied residual Igases to operate anexpansion engine and do not send such gases into the rectifying column; But. before using such residual gases to operate the err-I gine such residue or a portion thereof is passed through a part of the heat interchanging apparatus or mechanism to cool incoming new portions of air or other gases;

In this way a moderate compression only is required, after the apparatus has become properly cooled, in practice not much above 20 to 25' atmospheresJ With the apparatus illustrated in the drawing, the temperature of the'expa-nded obtainedin the third stage of hquefaction gases exhausted from the expansion. engine V Specificaiion of Letters Patent.

maintained at any point desired, and with Patented Aug. 31, 1915.

Application filed November'9, 1911. Serial No. 659,286; I

($ 09,210. The heat taken up by this unllquefied gaseous residue, is drawn from the a compressed air early in the stage of the process; and by cooling the compressed air at this early stage, the remnant of moisture left therein is practically all frozen out,

' which is necessary to the successful operation of all processes for liquefying air; and

this heat taken up is afterward converted into recoverable external work in expandin this unliquefied and partially re-heate compressed gaseous residue in the engine.

In the first stage of liquefaction in the liquefying coils, which are exposed to the cold expanded exhaust gases from'the engine, portions only of the air'or other gas are liquefied, and both the liquefied and unliquefied gases in the coils travel in the same direction and downwardlythe first. by gravity and the latter by force of pressure; so also in the second stage of liquefaction,

during thermal but not physical contact with the previously liquefied gasesbeing fractionally evaporated, as further portions of the unliquefied gases are liquefied, both gases and liquid pass helically downward 1 through the liquefying cone-coils, in contact Witheach other and-preferably in the same direction. .And after separatin the liquid .90 thus obtained from the unlique ed residue,

the third stage of liquefaction takes place,

for the lmliquefied compressed residue is' then further subjected to thermal but. not

physical contact with a colder evaporating liquid gas, so that further portions of this unliquefied residue -becomeliquefiedboth the newly liquefied and the unliquefied-gaseous residue being in contact with each other, and preferably being conducted downwardly in the same direction.

In the operation of my process, the hqmd is separated from the final unliquefied gaseous residue, and is released from pressure and delivered to the rectifying column, preferably near the top, where it is fractionally evaporated by condensing the. oxygen from the ascending vapors therein, and'in liquefying further portions of the unliquefied ases. g In order that those skilled in the art may understand and' make use of my invention, I will describe my improved process as illustrated by the accompanying drawing, in which I show in diagrammatic form the different parts of an improved apparatus whereby with suitable mechanism the process may be availed of. e

In the drawing, at the numeral 1 I show an ordinary 2-stage air compressor, capable of compressing the air or any other gaseous mixture to a suitable pressure and cooling it to normal temperature, this compressor being driven by an outside source of power, not shown in the drawing.

At 2 I show an air expanding engine of any suitable construction butpreferably of the vertical reciprocatin type; this engine is belted to the fly-whee of the compressor at 3 as shown, so as to do work in helping to drive the compressor.

At 4 and 5 I show drying drums,.charged respectively and preferably with calcium chlorid and caustic potash, for absorbing moisture and CO gas from the compressed air to be treated; at 6 I show a freezing drum which takes the partially dried air asexplainedlater on, and in which is the highpressure freezmg coil 7; and at 81- show a counter-current heat interchanging lowpressure drum, in which is the compressed air cooling'coil 9.

At 10 I locate the expanded air cooling drum, and within the same at 11 is the firststage liquefying high-pressure coil, withinwhich is partially liquefied the-compressed a-1r passing downwardly therein in countercurrent to the upwardly passing cold ex panded %ses in the drum 10' from the engine 2. ortions of thecompressed air are thusliquefied as'they pass downwardlyin the coil 11, and both liquefied and unliquefied are connected through the connecting pipe 12, to the upper coils of the helical cone-coil l-iquefier 13, .which is preferably made in form of an inverted hollow frustum of a cone. Both the liquid produced and the unliquefied gases pass together downwardly, in nearly a horizontal course but helically down into the partially orwholly submerged high-pressure receiving tank 14. In this receiving tank .are separated the unliquefied residual gases of the air or other mixture from the 1iquefied-the latter being produced in coils 11- by the cold expanded gases, and in the cone-coil liquefier 13 by liquefied-gases released from pressureland bemg fractionally evaporated thereby. This oxygen liquid in'this holder is withdrawn through the siphon tube 16 and its outlet delivery cook 17 and the holder may be kept full as shown or only partially full as at 18. Thus the liquid under pressure in the tank 14 is sub-cooled by the liquid in the holder 15, which sub-cooling tends tolessen the proportion of this liquefied gas under pressure in tank 14 which will vaporize when released from pressure.- The outlet for the liquid collected in the receiving tank 14 is through the siphon tube 19 and the re leasing valve 20, where it trickles or drips down after being released from pressure, through the glass. or metal balls 21 in the middle part 15 of the rectifying column, rectifying or condensing the oxygen in the ascending vapors in the column, and'coming in thermal contact with the gases in metal ring chambers 22,22 and 22 and :connecting upright tubes 23 and 23 which constitute the final or third stage liquefier. It will be noticed that. all vapor from the liquid gas as released from pressure through valve '20 and the spray-head 26, are utilized for their refrigerative efi'ect tohelp cool the incoming compressed air, both that to be liquefied and that to be expanded, for they pass-eventually into and through the inter- .changer cooling drum 8. p The liquefied gases as delivered from the cone-coil second stage liquefier 13, settle by "gravity to the bottom of the tank 14, (and this tank should be allowed to be only partially full-never above the outlet end of the delivery pipe from the coils 13), while the unliquefied gases pass up through the pipe 24 and valve 25, into the third stage liquefier, or ring chamber 22 and the numerous upright connecting tubes 23 and 23', wherein portions of this gaseous residue are'li'quefied by comingin thermal but not physical contact with the descending liquefied gases released through the valve 20 and sprayhead 26, suchliquefied portions collecting in the chamber 22. The liquid is discharged from this chamber or reservoir 22 into the top part 15 of the rectifying column, through the pipe 27, valve 28 and sprayhead 29, and as it trickles or drips down through the balls 21 it is subjected to fractiona-l distillation by condensing the oxygen of ascending vapors, and vaporizing the nitrogen or more volatile portions of the said descending liquid bothin 15 and 15; and finally as this liquid and the-liquid released from the valve 20, passes down over the radially grooved deflector 30 and over the inside surfaces of the helical coils 13, (nearly perpendicular to the course or direction of the gases passing through said helical coils), the liquid-gathered in the holder pipe 31, and being very cold this escaping gas passes down through the heat inter changing drum 8, and cools the incoming has become practically pure oxygen liquid'through the rectifying processes.

The more volatile gas, which, when air is treated, is nitrogen, passes from the rectifying column out at the top through the supply of compressed air in the coil 9, passing in a contrary direction thereto. It then passes through the conduit 32, and down successively over the drums 5 and 4, and outv through the drum casing 33 at 34, its ternperature in its course having'risen to prac-' ing chamber 22through the pipe 35 and valve 36; or it may be taken lower down,

' through valve 37, or may be'partially taken still lower down, before entering the third stage liquefying tubes 23 and 23', from pipe 24 through valve 44 and pipe 45; the preferred method, however, is to take it through valve 36, as it is desirable to take it.after it has beenv subjected to the third stage of liquefaction. residue, under compression and intended for expansion is then conducted through valve 40 and pipe 38 to the freezingcoil 7 in the drum 6, and thence through pipe 39. and valve 41 .to the engine. This residual portion of the air or other gas is, as will be seen,

partially "re-heated in passing through the coil 7, by cooling and freezing out the rest' of the moisture in the compressed air or other gas being used; but if the temperature given it is too high, such initial temperature before expansion in the engine may be regulated as desired by partially opening valve 42 and taking some of the gas direct from pipe 35. The cold expanded gases from the engine are delivered to the drum l0 through the exhaust conduit 43, and after cooling and liquefying portions of the. air in the first stage liquefying coil 11, 'pass through conduit 46 to the top of the heat interchangerdrum'S and out through conduit 3 as before stated.

The moisture extracted from the compressed air in the high-pressure drum 6, will gather as frost on the extremely cold coils 7; and thismaybe readily removed by closing valve-47 in the compressor discharge pipe 48 and valve 49 in the compressed-air supply 'pipe leading to the freezing drum 6, and valve 50 in the supply pipe 59 leading from said drum, and opening valve 52 and dripc'ock 51, and then passing air from the compressor before it is cooled, through the by pass 53 to the drum 6; the frost will then be quickly melted, and the resultant water drawnofi through drip valve 51. At 54 I show an inletcheck valve for sup- This \cold 'unliquefied finalv plying air, or any other gaseous mixture used, to the air compressor; and at 55 I show a check valve in the nitrogen outlet conduit 31, so as to regulate a slight back a pressure in the rectifying column 15, to

cause the oxygen liquid in the holder 15 to be forced out through the siphon tube 16 andwxygen delivery valve 17, when desired. At 56 and 57 are drip cocks for draining the moisture extracting drum 4 and the carbon. dioxid extracting drum 5, respectively.

All parts of the apparatus which in operation are below normal temperature, are

1. The process of liquefying air and separating thesame into its constituents, oxygen and nitrogen, whlch comprises compressing the air and cooling the same; then liquefying a portion of said cooled con1- pressed air in contact-With the unliquefied residue, and successively reheating and expanding the unliquefied residue with production of recoverable external work-that portion which is successively liquefied being liquefied by causing it to give up heat to-the successively preceding unliquefied expanded residue.

2. The process of liquefying air and separating the same into oxygen and nitrogen, which comprises compressing the air and cooling the same and then liquefying a portion thereof under compression and in contact With the unliquefied portion; then reheating the cold unliquefied portion and expanding the same against external resistance and thereby converting into recoverable work heat taken up by it in reeating before expansion; and finally causing this cold unliquefied expanded portion to liquefy other portions of the cooled compressed air previously cooled by said unliquefied portion in re-heating it before expansion.

3. The process of liquefying air and sepa rating itinto oxygen and nitrogen, which tially liquefy further compressed air.

4. The process of liquefying air and separating it into oxygen and nitrogen, consisting of or including the method ofcompressing air and cooling it down to its temperature of. liquefaction for the compression used, and liquefying a portion thereof, by

&

causing it togive up heat to cold expanded panding said re-heated unliquefied gases,,

with production 'of recoverable external work; and finally causing the unliquefied expanded gases thus cooled, to cool the successively following compressed air to be liquefied I or expanded.

5. The process of liquefying air and separating the oxygen from'the nitrogen thereof which comprises compressing and cooling the air, and then liquefying portions thereof While under pressure by bringing it in thermal but not physical contact with a descending or dripping liquefied gas being fractionally distilled or evaporated by heat drawn from the compressed air being liquefied, and then afterward liquefying other portions of said compressed air by passing it through a body of liquefied gas released from pressure.

6. The process of liquefying air and separating theoxygen from the nitrogen thereof which consists in liquefying portions of the air in two stages-one portion being liquefied by coldexpanded gas, and the other portion by a liquefied gas being evaporated by heat derived from the portion being liquefied thereby; and then finally liquefying a portion of the unliquefied residue.

'7. The process of separating a gaseous mixture into its constituent parts, which consists in compressing and cooling the same, partially liquefying the same in a hquefier, thereafter subjecting it to further partial liquefaction in another liquefier, separating the liquefied from the unliquefied portlon, using the unliquefied portion to cool additional previously compressed portions thereby reheating said unliquefied portion, expanding the said unliquefied portion to recool the same and employing such expanded portion to cause partial liquefaction in the liquefier first above mentioned.

8. The process of separating a gaseous mixture into its constituents oxygen and nitrogen'which consists in compressing and cooling the same, ,partially liquefying the same in a liquefier, conducting the liquefied and the unliquefied portions to a second liquefier and causing in such second liquefier further partial liquefaction of the same therein, separating the liquid from the unliquefied portion, conducting the unliquefied portion to a third liquefier and partially liquefying. the same therein, separating the last mentioned liquefied and unliquefied portions, using the said last mentioned unliquefied portion to cool additional previously compressed portions and thereby reheating the said last mentioned unliquefied portion, expanding the said last mentioned unliquefied portion to re-cool the same, and employing such expanded portion to cause partial liquefaction in the liquefier first above mentioned. 7

' 9. The" process of separating a gaseous mixture into its constituent parts which consists in compressing and cooling the same, partially liquefying the same in a liquefier and conducting the said liquefied and unliquefied portions in contact With'each other to a second liquefier in which the mixture is further partially liquefied, separating the liquefied from the unliquefied portion, releasing the liquefied portion from pressure, subjecting the said unliquefied portion to further partial liquefaction, separating the liquefied and the' unliquefied portions thus produced, releasing the liquefied portion from pressure, using hte last mentioned unliquefied portion to cool additional previously compressed portions and thereby reheating said last mentioned or unliquefied portion, expanding the said unliquefied portion to re-cool the same and employing such expanded portion to cause partial liquefaction in the liquefier first above mentioned.

Signedat New York city in the county of New York and State of New York this 24th day of October A. D. 1911.

t JAMES F. PLACE. Witnesses J. G. GADsnE-N, CLARENCE Pinon 

